Capturing LiDAR‐Derived Hydrologic Spatial Parameters to Evaluate Playa Wetlands

Abstract

The digital elevation model data from traditional stereo photogrammetric methods are inadequate in providing accurate vertical parameters to feed hydrologic models for low‐lying, extremely flat areas. High‐resolution light detection and ranging (LiDAR) data provide the robust capability of capturing small variations in low‐relief playa wetlands. The Rainwater Basin in south‐central Nebraska includes a complex of seasonally shallow playa wetlands that attract millions of migratory waterfowl every spring and fall. This research focuses on the development of a procedure with applicable protocols to produce LiDAR‐derived three‐dimensional wetland maps and to extract the critical surface parameters (i.e., watershed boundaries, flow direction, flow accumulation, and drainage lines) for playa wetlands. The topo‐hydrologic conditions of playa wetlands were evaluated at the watershed level. The results show that in the Rainwater Basin, 70.7% of the historic hydric soil footprints identified in the Soil Survey Geographic (SSURGO) database were not functioning as topographically depressional wetlands. This finding was confirmed by a recent five‐year Annual Habit Survey showing that 69.8% of the historic hydric soil footprints did not function during the spring migratory bird seasons between 2004 and 2009. The majority of playa wetlands' topographic conditions have been substantially changed and the SSURGO data cannot fully reflect current topographic reality in the Rainwater Basin.

A significant nexus: Geographically isolated wetlands influence landscape hydrology

“…Assuming cylindrical basins overestimates the buffering effect of more bowl-shaped basins since the total inundated area (with S y $ 1.0), and thus the area that provides hydrologic capacitance, decreases with stage. This effect is likely small in GIWs with relatively flatbottomed topography (e.g., playa wetlands [Tang et al, 2013] and prairie potholes [Shaw et al, 2012]). However, where basin shapes are more convex (e.g., coastal plain ponds [Schneider, 1994] [ Watson et al, 1990]) overall landscape hydrologic capacitance would decrease as a function of inundated area (e.g., a landscape with A total 5 40% would begin to behave more similarly to a landscape with lower total area as wetland stage declines).…”

Examining Playa Wetland Inundation Conditions for National Wetland Inventory, Soil Survey Geographic Database, and LiDAR Data

“…The LiDAR-derived depressions were used to compare with actual inundation or wet conditions of playa wetlands. This study adopted the methodology developed by Tang et al (2014) to calculate the theoretical depressions from the LiDAR data. With the geospatial calculation protocol, the sinks in LiDAR-based Digital Elevation Models (DEMs) were filled and zonal differences were recognized.…”

“…The depressions are geospatially overlaid with the SSURGO dataset, NWI dataset, and the actual inundation conditions to test the reliability of the in-depth hydrologic parameters drawn from LiDAR data. By using the LiDAR data with the procedures developed by Tang et al (2014), the depression layer was produced with a total area of 110,399.7 ha, representing the hydrologically possible depressional area.…”

“…The Rainwater Basin wetland complex encompasses 15, 907 km 2 land across 21 counties in south-central Nebraska (Tang et al 2012(Tang et al , 2014. The location map is shown in Fig.…”

Drainage Structure Datasets and Effects on LiDAR-Derived Surface Flow Modeling

“…The depression storage volume affects the amount of water stored or intercepted by land depressions (such as impoundments along road ditches and water puddles). The following steps were implemented for the modeling [22]:…”